1. Field of the Invention
The invention relates generally to rupturable fluid flow indicators and, more particularly, but not by way of limitation, it relates to an improved form of burst disk sensor for ultra low pressure applications wherein the burst strength of the sensing membrane is removed from the equation and only the strength of the conductor is in contention thereby to provide an electrical indication at a preselected break strength point.
2. Description of the Prior Art
Safety pressure relief apparatus of the rupturable type has often been utilized in applications where continual indication of the operating condition of the apparatus is desirable or necessary. Fluid pressure rupturable apparatus generally includes one or more rupture disks sealingly clamped between annular supporting members or heads which are then bolted together or suitably clamped between bolted flanges in a conduit or flow line. Thus, when a rupture disk fails, an indication of the failure may not be given other than by the resulting change in the vessel or flow line pressure. In some situations, the pressure condition of the system may not change appreciably and the failure of a rupture disk could go unnoticed for a considerable period of time.
Rupture disk monitoring devices and rupture disk alarm systems have been developed and utilized heretofore. For example, U.S. Pat. No. 3,770,918 is directed to a monitoring device for a reversible rupture disk that includes electric probes positioned behind the rupture disk. U.S. Pat. No. 4,342,988 is directed to a rupture disk alarm system that includes a signal carrying means in contacting relationship with a rupture disk. U.S. Pat. No. 4,408,194 is directed to a rupture disk monitor apparatus that includes capacitor means positioned in sensing relationship to a rupture disk. U.S. Pat. No. 4,978,947 is directed to a rupturable fluid flow indicator that includes a rupturable member having a plurality of openings formed therein and an electric current conductor attached to said rupturable member.
While the prior art rupture disk monitoring devices and systems have achieved varying degrees of success, they generally are not suitable or reliable in high temperature and/or highly corrosive applications, and they do not operate consistently unless full opening of the rupture disk occurs. Specifically, it is a problem to obtain a reliable break limit as well as an indication of rupture disk failure in very low flow pressure situations. Accordingly, the present invention provides an improved rupturable fluid flow indicator for use in ultra low flow pressure applications.